Yes you can
You can encrypt your Messenger Plus! chat logs so nobody else can view them.
Open the Plus! Preferences (type /prefs in a conversation window) and go to the Conversation tab then Chat Logs.
Enable them by Checking the box, then go to the next window Logs Encryption to create a password for them. This means only the person with the password can view them.
However, if you forgot the password you cannot recover the chat logs at all & this only works with Messenger Plus! chat logs. This means it wont work with WLM's logs and it requires Plus! to be installed.
Messenger Plus Download
http://www.msgpluslive.net/download/
Logs Encryption - More Info
http://shoutbox.menthix.net/showthread.php?tid=74210
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